A polymer that includes a double bond at the molecular terminal is used as a macromonomer when producing a polymer that has a branched structure (e.g., graft polymer or star-shaped polymer).
For example, Patent Literature 1 discloses a method for producing a polymer having a branched structure wherein a macromonomer is polymerized, the macromonomer including a group that includes a polymerizable carbon-carbon double bond at the molecular terminal. Patent Literature 1 discloses a method for producing a macromonomer wherein a vinyl-based monomer is polymerized using an atom transfer radical polymerization method that utilizes a polymerization initiator (e.g., organic halide) and a catalyst (e.g., transition metal complex) to obtain a vinyl-based polymer that includes a terminal halogen group, and the terminal halogen group is substituted with a compound that includes a double bond, for example.
When using the method disclosed in Patent Literature 1 wherein a functional group (e.g., halogen group) situated at the molecular terminal is substituted with a group that includes a carbon-carbon double bond, it is necessary to effect a functional group substitution reaction. Therefore, a method that introduces a carbon-carbon double bond into the polymerization-initiation terminal using a polymerization initiator that includes a carbon-carbon double bond has been studied in order to more easily obtain a macromonomer. Examples of such a method include an atom transfer radical polymerization method that utilizes an allyl halide as a polymerization initiator (see Non-Patent Literature 1). However, the type of vinyl-based monomer that can be applied to the atom transfer radical polymerization method that utilizes an allyl halide as a polymerization initiator is limited. Moreover, it may be difficult to control the polymerization reaction, or the polymerization reaction may not proceed depending on the type of vinyl-based monomer. In view of the above situation, a radical polymerization initiator that includes a carbon-carbon double bond, and can be applied to a wide variety of radically polymerizable monomers (e.g., vinyl-based monomer) to implement a controlled polymerization reaction, has been strongly desired.
However, since a radical polymerization initiator has reactivity with a carbon-carbon double bond, a radical polymerization initiator normally does not exhibit sufficient polymerization activity when a carbon-carbon double bond is introduced into the molecule of the radical polymerization initiator. Specifically, a radical polymerization initiator that includes a carbon-carbon double bond and has the desired properties has not yet been obtained.
An organotellurium compound is known as a radical polymerization initiator that makes it possible to subject a vinyl-based monomer or the like to radical polymerization while controlling the molecular weight distribution and the like (see Patent Literature 2 and 3).